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Discussion Starter · #1 ·
Hello all,

A couple of months ago I have bought a 2.3T Carlsson. Unfortunately it had a cracked head, so I decided to take the engine out and recondition it.

Now since this week, the engine is running with the balancer shafts removed, but I have some weird boost problems.

In the best case, it spikes to 1.1 bar and then goes immediately back to 0.8 where it tapers off. From 4500Rpm till the redline, I have only base boost (0.4bar). On other occasions, it only spikes to 0.7 bar

I have also tried the Abbott software to see if this makes a difference, however it seems to act the same way. In the best occasion I get a spike of 1.2, then a steady boost of 0.9 which tapers of to 0.6. In the worst case it doesn't spike beyond 0.7bar

On a friends car, it spikes 1.4 and gives almost a steady 1.0 with the Abbott software.

The only difference is that I have the TD04 turbo and that he has the uprated wastegate actuator.

Any ideas? Is my DI, solenoid or wastegate actuator dying? Maybe something elso to check?


Edited by Maarten on Marky's request.
 

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DI problems normally manifest themselves as more of a misfire- but there's no reason why you shouldn't try swapping a known good one just to eliminate it.

I'd be inclined to suspect an actuator/wastegate problem. Try (carefully) driving it with the w hose disconnected from the actuator and see if you get a uniform rise up to overboost cutoff. I had similar problems when I had my base boost set too low, and the actuator wasn't holding the wastegate shut properly.
 

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Discussion Starter · #3 ·
Thank you for your answer,

I have swapped the DI cassette and the solenoid valve today, but that doesn't seem to be the problem. The W hose disconnected gave a huge grin on my face, so I think the actuator is doing it's job. However I didn't had the guts to wait for the fuel cut, so I backed off before. The needle went towards the end of the red zone

Base boost is set at 0.42bar which seems to be correct. After driving it a couple of times, ISAT showed DI/APC fault code 44461, which means low boost, duh


Can it be a faulty knock sensor?
 

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Can it be a faulty knock sensor?  [/b]
The spark plugs are used as knock sensors...has the engine been built to the same spec as Saab intended....skimmed head will raise compression ratio which on boost will give detonation earlier..just a thought
 

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Mark,

AFAIK pre-Trionic cars still used a knock sensor on the block, not the plugs as the primary means of knock detection.

If it is the knock sensor, I believe it's possible to wire up an LED to indicate when knock is being detected. A search might find it.

Meanwhile, Marky, would this by any chance be the same car as you've also been having TCS problems with- because the two could be related.
 

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i wired up a LED to show when knock occurs on my pre-DI 9000. don't know if it is the same pins on my APC as yours. if you want details, pm me, of as here... either way..
 

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Discussion Starter · #7 ·
Originally posted by Mark E:
[qb]Meanwhile, Marky, would this by any chance be the same car as you've also been having TCS problems with- because the two could be related. [/qb][/b]
It is indeed the same car, but the TCS problems are already solved.

A couple of weeks ago, Isat showed up more then 20 fault codes
. After changing a lot of stuff I have it down to one srs fault code, which is less important at the moment.

This week I have done the following:

- Other DI/APC computer
- Other LH computer
- Swapped the TD04 for a T25
- Decat (cat was closed)
- Compression test (11, 10.6, 10.8, 11)
- fuel pressure test (ok)

But all to no avail

What I would want to know is what a healthy 2.3 carly should be boosting at 3000, 3500, 4000, 4500, 5000, 5500 and 6000RPM

On mine, it now spikes to 1.2 bar around 3000RPM. From 3000 to 3800 I have 1.0 bar, but then it tapers of very quickly. At 4000 I have only 0.8 bar and from 4500 to the redline (if it gets there
) baseboost (0.42).

I am sure this can't be normal?

I can only think of a couple of things that can be the cause:

- faulty sensor in the delivery pipe (which is used to calculate the boost)
- faulty knock sensor
- or maybe the easiest thing: engine knocking

Any other ideas? I am running out of options, and I'm starting to dislike the car or should I say lemon
 

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IIRC the DI/APC cars still used knock sensors in the ignition as that was part of the technology package that was developed along side the DI system with Mecel AB.

So perhaps a check to see if all the plugs are in good order?

Also to eliminate the possibility of detonation as a cause, try putting in a gallon or two of Toluene or Xylene. This will raise the octane rating sufficiently to eliminate any knock.

However if it were knocking I doubt it would be throwing codes at you. It's SUPPOSED to run low boost when knocking, and shouldn't cause a fault code of any kind.

Boost sensor sounds like a logical thing to try and replace. Also check for any pressure leaks between the turbo and engine?

Dubbya~
 

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Discussion Starter · #9 ·
Originally posted by Adrian W:
[qb]IIRC the DI/APC cars still used knock sensors in the ignition as that was part of the technology package that was developed along side the DI system with Mecel AB.  

So perhaps a check to see if all the plugs are in good order?   [/qb][/b]
The Di/APC cars have a knock sensor which is mounted on block itself. The function of the DI cassette which uses the plugs as knock sensors is not active.

However, I did have a look at the plugs and they are fine.

I know that DI/APC reduces boost when it monitors knock if a change of the timing isen't sufficient. I just don't understand why it should knock under the given circumstances. The lump is in great condition, and the head has been skimmed, but within factory limits. Also, since it reduces boost to base boost, it would mean that DI/APC is doing EVERYTHING it can to stop the engine from knocking. These facts make me believe that it's rather a faulty sensor.

As a part of the recondition, all vacuum hoses were replaced and no leaks can be found





 

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Discussion Starter · #10 ·
Boost sensor sounds like a logical thing to try and replace.  Also check for any pressure leaks between the turbo and engine?      

Dubbya~ [/QB][/b]
If it only was that simple The 91-93 DI/APC have no boost sensor. It calculates the boost with engine load compared to the air temperature in the delivery pipe. I will swap the sensor on monday, but the engine load can't be displayed or looked after. I am still trying to figure that out
 

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Originally posted by Marky:
[qb] QUOTE
Boost sensor sounds like a logical thing to try and replace.  Also check for any pressure leaks between the turbo and engine?      

Dubbya~ [/qb][/b]
If it only was that simple The 91-93 DI/APC have no boost sensor. It calculates the boost with engine load compared to the air temperature in the delivery pipe. I will swap the sensor on monday, but the engine load can't be displayed or looked after. I am still trying to figure that out [/QB][/b][/quote]There isn't a MAP sensor of any kind? Or a MAF sensor like the older C900's?

It really does sound like a faulty sensor. For what it's worth to my knowledge all Saabs that are capable of knock sensing have a microphone sensor on the block (or some other place) with or without the combination of the spark plug method.

Hafta reconsider adapting a DI casette to my C900 now as the IGS system is really what I wanted for it.

The engine looks in top notch shape. Even if there is no knock, it could be worth the effort to try the Toluene. Also to try a new throttle position sensor as that would be part of how the engine determines load. If I understand the way you explained the DI/APC system the TPS could be quite important and could be faulty?

Best of luck to you on it. If nothing else works, might take it to an independant shop or dealer.

p.s. Would this perhaps not get a better response in the 9000 section? Seems more a matter of repairs at this point than performance. Doesn't matter to me personally though.

Dubbya~
 

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Marky, I'm a bit suspect with the head. Was it measured before and after the machining? This is the only sure way to ascertain how much was removed - in any case, no more than .04 mm should be removed and much less is better. Could be that the increased compression is the knock culprit and the APC is just doing its' job. If you could quantify the exact amount taken off the head, a better handle could be had on the diagnosis.
 

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Having re-read the thread and mulled it over, I'm inclined to contemplate a fuelling problem. It seems to be OK at lower revs, but have problems at higher. A change of fuel filter and a dose of injector cleaner might help. If not, it may be a fuel pump problem.

Later Saabs dispensed with the block piezo sensor and relied on DI info for knock sensing.
 

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Discussion Starter · #14 ·
I have looked at the fuel system and put some injector cleaner in. Still nothing


However, I thought of the following: At idle, it seems that the engine misfires sometimes.

Can this be a timing issue?

I got several faultcodes today (as pre-ignition, knock sensor, tps signal, crank positioning sensor, etc...) which leads me towards that direction... The timing has been renewed together with the engine rebuild, so there is a chance that it's a teeth off..
 

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Discussion Starter · #15 ·
And it was the timing

The exhaust cam was one teeth off, I have put it right and went for a drive. She is finally boosting up to 5k Rpm before it tapers off.


Thank you all for the help!
 
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